N-vinylcaprolactam-acrylamide copolymer inhibition performance against 304L stainless steel corrosion in a simulated sweet-sour corrosive environment

Internal corrosion of oilfield pipes in the presence of CO₂ and H₂S is a significant problem in the oil and gas industry. The financial and material ramifications are immense, given that transportation pipelines are vital to the energy and gas industry. In typical oilfield industries, the prevailing approach to address corrosion issues affecting steel-based structural elements involves the incorporation of corrosion inhibitors into the corrosion system. In this study we evaluated the effectiveness of an N-vinylcaprolactam-acrylamide copolymer (NVAM) in inhibiting the corrosion of stainless steel in a 3.5% NaCl solution saturated with CO2 and containing 100 ppm H2S, which simulates a sweet/sour corrosive environment typical of oilfields Several experimental methods, such as weight loss, electrochemical techniques and surface characterization methodologies (SEM, EDS, & AFM) were used to assess the inhibitor's efficacy. The inhibitor demonstrated remarkable performance, attaining an approximately 90 % inhibition efficiency at a 100 ppm concentration. Adsorption of Poly(NVAM) adhered to the Langmuir adsorption model and functioned primarily as a cathodic inhibitor. The results obtained from the analysis of SEM, EDS, and AFM indicate that poly(NVAM) forms a protective film on the surface of the steel, thereby impeding the access of corrosive species. The protective film efficiently prevented corrosive chemicals from reaching the steel's surface.